Method of extracting and inserting upper and lower molds

ABSTRACT

A mold fixture  20  for safe and efficient extraction, insertion and storage of mold inserts  26, 28  is provided. The mold fixture  20  includes a lower receiving area  24  for fixedly receiving a lower mold insert  28 , an upper receiving area  22  for fixedly receiving an upper mold insert  26 . The mold fixture  20  facilitates insertion or extraction of the upper and lower mold inserts  26, 28  into/from a molding machine  1  in a safe and secure manner. Furthermore, the upper and lower mold inserts  26, 28  can be securely stored within the mold fixture  20  at a storage location.

This application is a Divisional of co-pending application Ser. No.10/367,900, filed on Feb. 14, 2003, the entire contents of which arehereby incorporated by reference and for which priority is claimed under35 U.S.C. § 120.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a mold fixture for use with alignment,installation, extraction, and storage of a mold tooling.

2. Description of the Background Art

Resin Transfer Molding (RTM) is a commonly used fabrication process forthe manufacture of fiber-reinforced composites. The resultinglight-weight, high strength parts are desirable for a variety ofapplications. Examples of such applications are commercial items such aschairs, automobile parts and aircraft components.

RTM is typically limited to low viscosity resin systems. The RTM processis fairly simple. A two-part, matched-metal mold (or tool) is made,which has a mold cavity conforming to the shape of the desired part. Apreform is placed into the mold cavity, and the mold is closed. Theresin is then injected under pressure through injection ports into themold and follows pre-designed paths, impregnating the preform. After thefill cycle, the cure cycle begins, during which the mold can be heatedand resin polymerizes to become rigid plastic. Both the mold and resincan be heated as needed for the application.

RTM tooling requires a method to align the mold halves, a way tointroduce resin in the mold, vents to let the air out, a seal to keepthe resin in the tool and a method of clamping the tool set together. Inaddition, the forces acting on an RTM tool demand a well-designedstructure including a substantial supporting framework. It is importantto establish a highly accurate mold set alignment during the moldbuilding sequence. An effective method of alignment is to use core boxpins. These pins are molded in the male and female halves of the toolset and provide an unchanging positive alignment.

RTM can utilize either “hard” or “soft” tooling, depending upon theexpected duration of the run. Soft tooling would be either polyester orepoxy molds, while hard tooling may consist of cast machined aluminum,electroformed nickel shell, or machined steel molds. RTM can takeadvantage of the broadest range of tooling of any composites process.Tooling can range from very low cost to very high cost, long life molds.

Well known in the art is the use of a mold base (or frame), whichreceives a mold insert (or die insert). Respective halves of the moldinsert form an internal injection cavity when clamped together. In orderto re-tool a molding apparatus, for example when the desired product ischanged, the mold inserts are removed from the mold base and replacedwith a different set of mold inserts. An example of such mold frames andmold inserts are those made by the Master Unit Die Products ofGreenville, Mich. identified as “MUD” (Master Unit Die) frames and unitdie inserts. These frames and inserts are designed to be used inmatching pairs wherein the large frames are each arranged to accommodatein a recess of the frame a corresponding die insert.

In order to maintain dimensional stability, the frames are of a heavyconstruction, generally steel, and, in order to change from one size dieinsert to another die insert, the first die insert is removed from theframe and replaced with a second die insert.

Because this operation involves a substantial rearrangement of themolding machine and involves the handling of a heavy frame, the operatortime and down time for the molding apparatus are a substantial part ofthe molding process. In particular, because such a changeover may occurdaily or even more than once a day, the changeover time is a significantpart of the cost of producing the molded product.

Furthermore, in view of the heavy weight of the mold, it is difficult toplace the mold into the molding machine and to remove the mold from themachine when the machine is to be used to form a different part. If themold is not raised and lowered carefully, and because of the heavyweight of the mold or mass imbalance, it becomes very difficult toreplace the mold without damaging the mold or the injection moldingmachine. Additionally, once the mold is removed from the moldingmachine, the mold must be stored, which is conventionally done byplacing the mold onto a pallet and transporting the mold to a storagelocation.

U.S. Pat. No. 5,992,208 discloses a press arrangement that has slidingtables. These sliding tables carry molds between press stations and areprovided in the press stations. An intermediate station is arrangedbetween press stations, this intermediate station containing workpieceholders for the workpiece transport. There, however, arises the problemthat the heavy mold must be slid across the sliders by the operator,which can result in injury. Furthermore, there is no provision forefficiently removing the mold from the press arrangement safely andsecurely, nor are there any provisions for storing the mold once it hasbeen removed.

Because tooling cost and start up time comprise a substantial portion ofthe cost associated with RTM, a need has arisen for safer and fasterinitial setups, production changeovers, and storage.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a moldfixture that is utilized for safe and efficient extraction, insertionand storage of mold inserts. The mold fixture includes a lower receivingarea for fixedly receiving a lower mold insert, an upper receiving areafor fixedly receiving an upper mold insert. The mold fixture facilitatesinsertion and extraction of the upper and lower mold inserts into/from amolding machine in a safe and secure manner. Furthermore, the upper andlower mold inserts can be securely stored within the mold fixture at astorage location.

Further scope of applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus, are not limitiveof the present invention, and wherein:

FIG. 1 is a pictorial view of a resin transfer molding apparatus;

FIG. 2 is a perspective view of a mold fixture, according to a preferredembodiment, having a lower mold insert attached thereto;

FIG. 3 is a perspective view of a mold fixture having an upper and lowermold insert attached thereto according to a preferred embodiment;

FIG. 4 is a top view of a mold fixture according to a preferredembodiment;

FIG. 5 is a front view of a mold fixture according to a preferredembodiment;

FIG. 6 is a side view of a mold fixture according to a preferredembodiment;

FIG. 7 is a process diagram outlining an extraction process of moldinserts according to a preferred embodiment; and

FIG. 8 is a process diagram outlining an insertion process of moldinserts according to a preferred embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows an example of a resin transfer molding apparatus 1, whichis suitable for implementing principles of the present invention. Rawmaterial, typically resin, is loaded into a hopper 3 attached to anextruder 4. An extruder screw 5 feeds resin from the hopper 3 andprogressively heats the resin as it is transported down the length of abarrel 6. The resin is then transported into an accumulator 8. The resinmelt pressure created by the extruder 4 forces a piston 7 inside theaccumulator 8 back to a desired position. Once the desired volume ofresin has been accumulated, the accumulator piston 7 moves forward andforces the volume of resin through a transfer pipe 9 into a cavity of amold 10. Temperature is controlled using heat exchange coils 11. Anarrangement of valves (not depicted) is provided in relation to thetransfer pipe 9 to control flow and backflow of the resin, respectively.The part (or preform) to be infiltrated is contained within the mold 10.The mold 10 is contained or located within a press 12. The press 12 canbe a hydraulic press. Although a vertically acting press is depicted inFIG. 1, a horizontally acting press can also be used. The clamping forceof the press 12, which, for example, has a 500 ton clamp forcecapability, counteracts the pressure of the resin being forced into themold cavity. The infiltrated part remains within the mold 10 until theresin cools below the melting point, and the part is then removed.Throughout the several views, like parts will be assigned like referencenumerals.

FIG. 2 is a perspective view of a mold fixture 20 according to apreferred embodiment of the present invention. The mold fixture 20includes upper and lower receiving areas 22, 24 for receiving upper andlower mold inserts 26, 28, respectively. These upper and lower moldinserts 26, 28 can typically each weigh 160 pounds or more, depending onthe size of the desired product or application and are fastened to amold or mold frame (not shown) in accordance with conventionaltechniques. The upper and lower receiving areas 22, 24 are operativelyconnected to one another via press safety restraints 30. The presssafety restraints 30 provide structural support such that the upper moldinsert 26 is securely spaced from the lower mold insert 28, andfunctions as a stop when the press 12 is lowered during an extraction orinsertion operation, which is described further hereinbelow.Additionally, front and rear apertures 32, 34 are formed between theupper and lower receiving areas 22, 24 having a height that isdetermined by the height of the press safety restraints 30.

The mold fixture 20 further includes insert alignment tabs 36 forpositioning the upper and lower mold inserts 26, 28 onto the upper andlower receiving areas 22, 24, respectively. Upper and lower insertattachment points 38, 40 are positioned in conjunction with the insertalignment tabs 36 in order to secure the upper and lower mold inserts26, 28 to the mold fixture 20. These upper and lower insert attachmentpoints 38, 40 are preferably screw type bolts.

Adjustable mold alignment feet 42 are operatively connected to the presssafety restraints 30 in the lower receiving area 24. The adjustable moldalignment feet 42 are also provided on each end of a lower crossmember44, which traverses the lower receiving area 24 in a horizontal plane.The adjustable mold alignment feet 42 have a tapered end 46 and analignment face 54 in order to facilitate positioning of the mold fixture20 onto the mold or mold frame. Furthermore, the adjustable moldalignment feet 42 have a height greater than a thickness of the lowermold insert 26, such that when the mold fixture 20 is utilized forstorage, a lower surface 48 of the lower mold insert 28 is unobstructedand is free from any force.

Upper and lower spring loaded insert clocking pins 50, 51 are providedon the upper and lower receiving areas 22, 24 for facilitating initialupper or lower mold insert 26, 28 attachment to the mold fixture 20, forexample, when a mold insert must be removed from the mold fixture 20 forrepair or when a new mold insert is attached to the mold fixture 20.When, for example, a new mold insert is attached to the mold fixture 20,the mold inserts must be angularly aligned in order to achieve thecorrect positioning of the mold inserts. This is performed by rotatingeither the upper or lower mold insert 26, 28 on the mold fixture 20within the insert alignment tabs 36 until either the upper or lowerspring loaded insert clocking pins 50, 51 engage with an accompanyingslot (not shown) provided in the upper of lower mold insert 26, 28.Thereafter, the upper and lower insert attachment points 38, 40 areutilized to fixedly secure the upper and lower mold inserts 26, 28 tothe mold fixture 20.

FIG. 3 is a perspective view of the mold fixture 20 having the upper andlower mold inserts 26, 28 attached thereto. With either one or both theupper and lower mold inserts 26, 28 securely attached to the moldfixture 20, the mold fixture 20 can be transported onto and from thepress 12, to and from a storage location, by a transport device (notshown). The transport device, such as a forklift, is able to receive themold fixture 20 thereonto by inserting forks through the front and rearapertures 32, 34. Additional transport configurations, providing secureand safe transport, may also be facilitated.

FIG. 4 is a top view of the mold fixture 20, which has the upper moldinsert 26 shown attached thereto. It can be readily seen, and referringto FIGS. 5 and 6, that the adjustable mold alignment feet 42 arepositioned such that they do not interfere with the lower mold insert 28because they are positioned at a distance, on the mold fixture 20,greater than a diameter 52 of the lower mold insert 28. Furthermore, theadjustable mold alignment feet 42 can be adjusted in a horizontal andvertical direction.

Referring to FIG. 7, an extraction operation of the mold inserts 26, 28will now be explained. First, in step S100, the press 12 is opened,separating the upper mold insert 26 from the lower mold insert 28, suchthat the mold fixture 20 can be moved therebetween. In step S102, themold fixture 20 is positioned into the space created by the opening ofthe press 12 via the use of a transport device, which utilizes theapertures 32, 34 in order to retain stability of the mold fixture 20,thereby eliminating mass imbalance. The transport device then lowers themold fixture 20 onto the lower mold insert 28, whereby the tapered end46 of the adjustable mold alignment feet 42 facilitates positioning ofthe mold fixture 20, e.g., within a few thousands of an inch to thedesired position, such that the alignment face 54 of the adjustable moldalignment feet 42 abuts a side surface (not shown) of the mold or moldframe. Next, in step S104 the lower mold insert 28 is securely fastenedonto the mold fixture 20 by the lower insert attachment points 40,which, as stated above, can be a screw-type bolt or other suitableattachment device.

After the lower mold insert 28 is securely fastened onto the moldfixture 20, the mold insert 28 is disengaged from the mold frame in stepS106. Thereafter, the press lowers the upper mold insert 26 onto theupper receiving area 22 of the mold fixture 20 in step S108. Then, instep S110 the upper mold insert 26 is securely fastened onto the moldfixture 20 by the upper insert attachment points 38. Once the upper moldinsert 26 is securely attached to the mold fixture 20, the upper moldinsert 26 is disengaged from the mold frame in step S112. The press 12is then raised in step S114 and the mold fixture 20 containing the upperand lower mold inserts 26, 28 can be removed from the press 12 andtransported safely and securely to a storage location in step S116.

Next, a mold insert insertion process will be explained with referenceto FIG. 8. In step S120 the press 12 is opened and the mold fixture 20containing the upper and lower mold inserts 26, 28 is transported by atransport device into the opening formed by the press. The mold fixture20 is lowered onto the mold or mold frame contained within the press 12in step S122, whereby the tapered end 46 of the adjustable moldalignment feet 42 facilitates positioning of the mold fixture 20, e.g.,within a few thousands of an inch, to the desired position such that thealignment face 54 of the adjustable mold alignment feet 42 abuts theside surface of the mold or mold frame. In step S124, the lower moldinsert 28 is fastened to the mold frame in a conventional manner.Thereafter, in step S126, the lower mold insert 28 is disengaged fromthe mold fixture 20 by disengaging the lower insert attachment points40. The press 12 is then lowered, in step S128, to a point where theupper mold insert 26 is positioned for attachment to the mold or moldframe.

The upper mold insert 26 is then fastened to the mold frame in aconventional manner in step S130, for example by spool locks (not shown)locking into spool scallops 56, which are provided on the upper andlower mold inserts 26, 28. Then, in step S132, the upper mold insert 26is disengaged from the mold fixture 20 by disengaging the upper insertattachment points 38. Next, the press 12 is raised in step S134 suchthat the upper mold insert 26 is lifted in conjunction with the moldframe away from the mold fixture 20. Finally, the mold fixture 20 isremoved from the press 12 by the transport device and placed in astorage location in step S136.

An additional advantage of the present invention is that the operatorchanging the upper and lower mold inserts 26, 28 does not have to waitfor either of the inserts to cool down from temperatures incurred duringa molding process, because the operator does not have to directlycontact the mold inserts during a change over process. Also, oneoperator is able to change the mold inserts, whereas conventionallyseveral operators were required. Therefore, change over time of the moldinserts can be reduced as compared to the conventional art.

Although an embodiment of the present invention has been described abovein the context of RTM, principles of the present invention may also beapplied to facilitate tooling in other environments, for exampleplastic, powder injection machines, or any molding machine that requiresmolds or mold inserts.

1. A mold fixture comprising: a lower receiving area for fixedlyreceiving a lower mold; an upper receiving area for fixedly receiving anupper mold; and mold alignment feet for facilitating positioning of saidmold fixture onto a molding machine, wherein said mold fixturefacilitates insertion or extraction of said upper and lower molds intoor from a molding machine.
 2. The mold fixture according to claim 1,wherein said upper and lower molds are upper and lower mold inserts. 3.The mold fixture according to claim 1, wherein said mold fixture furthercomprises: press safety restraints, which in combination with said upperand lower receiving areas form apertures within said mold fixture, saidapertures facilitating transport of said mold fixture by a transportdevice.
 4. The mold fixture according to claim 1, wherein said moldfixture further comprises: insert alignment tabs positioned on each ofsaid upper and lower receiving areas, said insert alignment tabsfacilitating a position of said upper and lower molds.
 5. The moldfixture according to claim 1, wherein said mold alignment feet areadjustable in a horizontal and vertical plane.
 6. The mold fixtureaccording to claim 1, wherein said mold alignment feet have a taperedend adjacent to an alignment face for facilitating alignment of the moldfixture.
 7. The mold fixture according to claim 1, wherein said moldfixture further comprises: a lower cross member, which traverses ahorizontal plane of said lower receiving area.
 8. The mold fixtureaccording to claim 7, wherein said lower cross member further includesmold alignment feet operatively attached to ends of said lower crossmember.
 9. The mold fixture according to claim 8, wherein said moldalignment feet each have a tapered end.
 10. The mold fixture accordingto claim 1, wherein said mold fixture further comprises upper and lowerinsert attachment points, for fixedly securing said upper and lowermolds, respectively, to said mold fixture.
 11. The mold fixtureaccording to claim 1, wherein said mold fixture further comprises upperand lower spring loaded insert clocking pins for fixing an angularposition of the upper and lower molds, respectively, onto the moldfixture.